Diaphragm construction for specimen bursting machines



y 3, 1950 R. E. GETCHELL 2,509,143

DIAPHRAGM CONSTRUCTION FOR SPECIMEN BURSTING MACHINES Filed Jan. 24'. 1949 JN VEN TOR.

' MZW sY z Patented May 23, 1950 DIAPHRAGM CONSTRUCTION FOR SPECI- MEN BURSTIN G MACHINES Raymond E. Getchell, Holyokc, Mass, assignor to B. F. Perkins & Son, Inc., Holyoke, Mass, a corporation of Massachusetts Application January 24, 1949, Serial No. 72,293

2 Claims. (01. 137-157) This invention relates to improvements in testing machines and is directed more particularly to improvement in such machines where a specimen is ruptured by a flexible diaphragm which is subjected to pressure.

The principal object of the invention is directed to the provision of a diaphragm construction for a testing machine which in itself does not resist the pressure employed to distend the diaphragm for rupturing the specimen.

U. S. Patent 1,878,446 of September 20, 1932 shows a testing machine having a platform to which a specimen of paper is clamped by clamp 18 with a diaphragm 8 below the specimen which is distended by fluid pressure to rupture the specimen.

The diaphragm has been made of rubber or rubber composition so as to be distendable but in all cases in itself it resists the pressure of the fluid so that the indicated pressure of the fluid at which the specimen is ruptured does not represent the true bursting pressure thereof.

According to this invention, a novel diaphragm construction is provided which has no resistance in itself to the action of the fluid pressure whereby the pressure of the fluid at the time of rupture of the specimen represents the true test of the specimen.

With the foregoing and various other novel features and advantages and other objects of my invention as will become more apparent as the description proceeds, the invention consists in certain novel features of construction and in the combination and arrangement of parts as will be hereinafter more particularly pointed out in the claims hereunto annexed and more fully described and referred to in connection with the accompanying drawings wherein the figure is a sectional elevation view through the platform of a testing machine embodying the novel features of the invention.

Referring now to the drawings more in detail, the invention wil1 be fully described.

A platform construction includes an upper flange member 2 having a specimen support 4 secured thereto by a ring 6 threadedly engaging the flange as shown.

A passageway 8 extends through the part 2 and the support 4 has an opening in in alignment therewith.

This construction corresponds generally with that of U. S. Patent 1,878,466 above referred to and to that in U. S. Patent 1,758,688 of May 13, 1930. r

Fluid such as liquid or the like is moved upwardly of the passageway 8 to act on a diaphragm between the members 2 and 4 for distending the same upwardly for rupturing or bursting a. specimen clamped to member 4 by a clamp.

According to this invention, a diaphragm I2 has a peripheral bead l4 disposed in an annular groove l6 provided in the members 2 and. 4 and a marginal portion l8 therebetween.

An intermediate portion 20 extends downwardly in the passageway 8 and is turned at 2| providing an upwardly extending portion 22 with a central portion 24 centrally of the passageway.

The diaphragm will be formed from pliable material such as rubber, rubber composition, synthetic rubber or the like so as to be impervious to the pressure of fluid applied to the lower side thereof.

Preferably the diaphragm will increase in thickness from the portion [8 thereof to the central portion thereof somewhat as shown. The peripheral portion thereof will be restrained in the annular groove it while the portion l8 will not1 riecessarily be clamped between members 2 an As pressure is applied to the lower side of the diaphragm the central portion 24 is elevated for acting on the specimen by a relative rolling or folding action of the portions 20 and 22 thereof.

As above stated, the diaphragm of the prior art is caused to stretch as pressure is applied thereto and has an inherent resistance in distending to engage and rupture the specimen.

As distinguished from the prior art diaphragm, that of this invention does not resist the action of the fluid but is distensible without ofiering resistance. The central portion is elevated for the reason the fold 2i moves upwardly.

The physical dimensions of the diaphragm are not changed as when the prior art diaphragm is distended by stretching. Instead portions of the diaphragm are displaced without stretching therefore the diaphragm offers no resistance.

Altogether the diaphragm functions to act on and rupture the specimen so that the pressure at which the specimen ruptures bears a definite relation to the strength of the paper. That is, the pressure at which the speciman ruptures with reference to the area of opening Ill may be taken as an indication of the strength of the specimen.

The invention may be embodied in other specific forms without departing from the essential characteristics thereof. Hence, the present embodiments are therefore to be considered in all respects merely as being illustrative and not as :being restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all modifications 1. A diaphragm for a testing machine wherein i the diaphragm is acted upon by iiuid pressure for rupturing a specimen comprising,. a circular member made from pliable material to have peripheral, intermediate and central portions, said peripheral portion provided with a peripheral bead, said intermediate portion extending downwardly from and within the peripheral portion and doubled upon itself to extend upwardly and connected at upper end to said central portion, said intermediate portion gradually increasing in thickness from the peripheral portion to the central portion which is of greater thickness than said peripheral portion.

2. A diaphragm for a testing machine wherein a diaphragm is acted upon for distension to rup- 4 ture a specimen comprising, a circular diaphragm member formed from pliable material to have peripheral and intermediate and central circular portions, said intermediate portion having an outer portion extending downwardly from the plane of the upper side of the peripheral portion and doubled upon itself to provide an inner portion extending upwardly to said central portion, said central portion disposed in a plane adjacent the plane of the upper side of the peripheral portion, said intermediate portion increasing-in thickness downwardly and upwardly from the peripheral to the central portion.

RAYMOND E. GETCHELL.

REFERENCES CITED The following-references are of record in the file of this patent:

UNITED STATES PATENTS 

